Coraciiformes Taxon Advisory Group -

Description

Green woodhoopoes
are a medium sized bird averaging 12 inches long with an equivalent wingspan.
Their weight averages between 60 - 70 grams depending on gender. Adult
plumage is overall dark green with glossy reflections of purple, black,
and green. Wings are rounded with white bars crossing mainly the primary
feathers. Tail is graduated with white spots and is generally longer than
the body. Adults have a distinctive long, red, decurved bill, which is
longer in males than females. Bill color varies from bright red to dull
black depending on age and sub-species. Their short red legs are a bright
contrast to the dark plumage. Immature birds are generally much duller
in color and instead have straight, black bills and black legs.

Status

Studies
have shown their lifespan to be around 8 years due to heavy predation.
Breeding success and life expectancy are affected by several factors including
predation and competition. Driver ants have shown to be nocturnal predators
of nestling woodhoopoes in nest holes. Predators to fledglings and adults
include Gabar goshawks, Harrier hawks, Pearl-spotted owls, genets and
mite infestations. There is often intense competition for proper nesting
sites between woodhoopoes and other bird species, mammals, and honeybees.
Green woodhoopoe annual numbers are further affected by parasitation by
Greater Honeyguides in Nigeria. According to Urban et al., their overall
mean annual survival is low. Currently they are not listed as a threatened
species.

Range

Woodhoopoes
are one of the few bird families that are found exclusively in Africa.

Habitat

Green woodhoopoes dwell in savannah, open woodland, palm groves, acacia thornvelds
and wooded garden areas. They are absent from arid zones and forest.

Behaviors

Green woodhoopoes
are highly sociable, chattering birds
(849kb WAV file) usually seen in small flocks of 4-15 individuals.
Groups are often seen following each other from tree to tree while foraging
in cracks and crevices. During the dry season they also forage on the
ground. The sex ratio in flocks is about 1:1 but as a rule only includes
one breeding pair. They climb trees in a jerky fashion similar to woodpeckers;
often dropping perpendicularly along the trunk and then clinging to the
bark with their sharp, curved claws and using their tail as a prop.

They are
generally known as one of the noisiest birds of the bush, with their old
African regional name 'Kakelaar' being derived from its voice. Their displays
include a loud 'kuk-uk-uk-uk' cackling call; starting off slowly then
with a crescendo as a group as the birds rock back and forth with their
heads lowered. They also have a distinct musky scent they produce from
their uropygial gland that is often used for defense from predators. A
nestling's defense consists of squirting large quantities of smelly excrement
when taken from the nest.

These birds
are highly territorial with each flock usually defending the same large
area throughout the year. Territorial defense is through group displays
with birds often passing lichens or bark between themselves to increase
group cohesion. Sexes generally roost separately. When vacancies in flocks
occur through predation, they are usually filled by birds of the same
sex from nearby territories. Members of flocks tend to be very closely
related. Unrelated females sometimes break off to form new flocks.

Reproduction

In any given
territory there is generally one monogamous breeding pair, usually the
oldest birds. Prior to breeding, the pair leaves the group to forage and
allopreen quietly on their own with the male frequently offering food
to the female. During this time, the non-breeding members of the flock
are scouting for nesting sites while foraging. Nest sites chosen are usually
closest to the most concentrated food source in the territory. The unlined
nest of choice usually consists of a natural live tree cavity or an old
nest hold from a woodpecker or barbet.

The average
clutch size is 3-5 blue-green eggs about 25x18mm. Pairs can produce two
clutches per year in a bountiful season. Breeding usually occurs during
the rainy season (July through October depending on the geographical area).
Incubation by the female starts with the complete clutch and lasts for
17-18 days.

These birds
use a cooperative breeding system in which the breeding pair will have
help feeding their young from typically 1-10 non-breeding birds, including
their offspring from previous clutches. The male and helper birds will
forage for food and bring it to the female who relays it to the altricial
chicks. Just prior to fledging, all of the members of the flock call extensively
to the young and preen them. This appears to prepare them for integration
into the group. Fledging occurs at 28-30 days. The young are protected
and fed by all members of the flock for several weeks after fledging.
A few months later the fledglings will, in turn, contribute food to the
next group of hatchlings. They will remain with the parents for 1-5 years
as non-breeding helpers.

Green Woodhoopoes
have successfully bred in both free-flight aviaries and smaller well-planted
enclosures (smallest averaging 4' x 10' x 10') when isolated into pairs.
When provided a variety of nest boxes and palm logs in larger aviaries,
they will generally inspect each one to their liking. Both should average
about 12-18''deep with a 2-3'' diameter hole and can be 10-12'' square.
There are obviously exceptions with some pairs choosing boxes that weren't
meant for them. The birds nest in unlined cavities but they will usually
excavate shaving if placed in the box.

Breeding
pairs can frequently have multiple clutches per season. The adult pair
and the eldest clutch of fledged chicks can generally be maintained together,
but it is advisable to remove these older chicks when the subsequent clutch
is ready to fledge. The breeding pair can be aggressive to and sometimes
kill the older chicks. Same-sex pairings of adult green woodhoopoes have
been successful in both large and small aviaries.

Although it is typically possible to house the primary breeding pair of green woodhoopoes with previous offspring during breeding season, there are instances of this not being successful. The possibility of the adult birds attacking the juveniles exists, as does the possibility of the juveniles predating the newly hatched chicks. Video of this predation can be viewed by clicking here (14mb Windows Media Player File) . The good news of this video, due to the nest observation camera the chick taken was able to be retrieved unharmed and returned to the nest and the juvenile female responsible was removed from the enclosure.

Diet

Their natural
diet consists of arthropods, insects, and occasionally lizards and vertebrates
probed out of crevices and fissures in bark, wood and grasses. They have
also been shown to drink nectar of Erythrina flowers and eat small fruits.
Diet for the young can include: caterpillars, grubs, insect egg masses,
beetles, termites, ants, and moths. For adults, prey is either swallowed
directly or first beaten against a branch.

Green woodhoopoes
are primarily carnivorous and insectivorous and their captive diet should reflect this. A variety of insects should
be provided such as waxworms, adult crickets and/or mealworms of various
sizes. Their diet should also include small pieces of bird-of-prey meat
(i.e. Nebraska brand), chopped greens and fruit, and soaked dog food and/or
soft-bill pellets. A sprinkle of vitamin supplement such as vionate, calcium
(especially important during nesting season), or Nekton I should also
be provided.

Current
Captive Population Status

In North
America there is a relatively small population of green woodhoopoes of varying
sub-species currently housed at approximately two dozen institutions. Of those, the majority of birds are captive hatches with a significantly smaller population of wild-caught specimens.

Their total population numbers
have increased sharply in the last few years. However, most of the living
individuals are derived from a small number of founders making the current
population very closely related.

Roughly
10% of the historical captive population have escaped from zoological
institutions (the majority of which have been recaptured), showing a need for care in choosing enclosures. Green woodhoopoes
explore their environment throughly due to their natural nature of being
foragers as well as having a healthy supply of curiosity. They often
inspect every inch of their enclosure from top to bottom and find weaknesses
that exist. Their body design allows them to slip into tight spaces that
either allows them escape, or equally as likely, entrapment. Birds that
are not seen for several days are sometimes found dead, wedged into spaces
that they were unable to escape from. They have also been known to chip
away at old, rotten wood thus making their own escape route. Always
inspect aviaries, introduction cages, and any other spaces they are housed
in for even the smallest openings.

A list of
current participating institutions in the Green Woodhoopoe PMP can be
found by clicking here.